Numerical study of concrete-filled steel composite (CFSC) stub columns with steel stiffeners is presented in this paper. The behaviour of the columns is examined by the use of the finite element software LUSAS. Results from nonlinear finite element analyses are compared with those from corresponding experimental tests which uncover the reasonable accuracy of the modelling. Novel steel stiffeners are used in the CFSC stub columns of this study. The columns are extensively developed considering three different special arrangements of the steel stiffeners with various number, spacing, and widths of the stiffeners. The main variables are: (1) arrangement of the steel stiffeners (C1, C2, and C3); (2) number of the steel stiffeners (2 and 3); (3) spacing of the steel stiffeners (50 mm and 100 mm); (4) width of the steel stiffeners (50 mm, 75 mm, and 100 mm); (5) steel thickness (2 mm, 2.5 mm, and 3 mm); (6) concrete compressive strength (30 MPa, 40 MPa, and 50.1 MPa); (7) steel yield stress ( 234.3 MPa, 350 MPa, and 450 MPa). Effects of the variables on the behaviour of the columns are assessed. Failure modes of the columns are also illustrated. It is concluded that the variables have considerable effects on the behaviour of the columns. Moreover, ultimate load capacities of the columns are predicted by the design code EC4, suggested equation of other researchers, and proposed equation of the authors of this paper. The obtained ultimate load capacities from the analyses are compared with the predicted values. It concludes that EC4 gives more conservative predictions than the equations.

Slender structural floors could experience irritating vibration problems due to human walking load and so, vibration acceptability of such floors is an essential subject in addition to the usual strength criterion. This paper focuses on the dynamic response of a lightweight composite structural system known as Profiled Steel Sheet Dry Board (PSSDB) to evaluate its vibration acceptability under human walking load. For this point, twelve (12) PSSDB panels in the category of Low Frequency Floor (LFF) were developed via Finite Element Method (FEM). The natural frequencies and mode shapes of the studied panels were determined based on the developed finite element models. For more realistic evaluation on dynamic response of the panels, dynamic load models representing human walking load were considered based on their Fundamental Natural Frequency (FNF), and also time and space description. The peak accelerations of the studied panels were determined and then compared to the limiting value proposed by the standard code of ISO 2631-2. Effects of changing thickness of the Profiled Steel Sheet (PSS) and Dry Board (DB), screw spacing, damping ratio, type of support, and floor span on the dynamic responses of the PSSDB panels were evaluated. According to literature, effect of presence of concrete on the dynamic response of the PSSDB system was revealed. The results demonstrated that although some factors reduced dynamic response of the PSSDB system under human walking load, low frequency PSSDB floor system could reach high vibration levels resulting in lack of comfortableness for users.

This paper investigates the behaviour of axially loaded stiffened concrete-filled steel composite (CFSC) stub columns using the finite element software LUSAS. Modelling accuracy is established by comparing results of the nonlinear analysis and the experimental test. The CFSC stub columns are extensively developed using different special arrangements, number, spacing, and diameters of bar stiffeners with various steel wall thicknesses, concrete compressive strengths, and steel yield stresses. Their effects on the columns behaviour are examined. Failure modes of the columns are also illustrated. It is concluded that the parameters have considerable effects on the behaviour of the columns. An equation is proposed based on the obtained results to predict the ultimate load capacity of the columns. Results are compared with predicted values by the design code EC4, suggested equation of other researchers, and proposed equation of this study which is concluded that the proposed equation can give closer predictions than the others.

This paper investigates the dynamic response of a composite structural system known as Profiled Steel Sheet Dry Board with Concrete infill (PSSDBC) to evaluate its vibration serviceability under human walking load. For this point, thirteen (13) PSSDBC panels in the category of Low Frequency Floor (LFF) were developed using Finite Element Method (FEM). The natural frequencies and mode shapes of the studied panels were determined based on the developed finite element models. For more realistic evaluation on dynamic response of the panels, dynamic load models representing human walking load were considered based on their Fundamental Natural Frequency (FNF), and also time and space descriptions. The peak accelerations of the panels were determined and compared to the limiting value proposed by the standard code ISO 2631-2. Effects of changing thickness of the Profiled Steel Sheet (PSS), Dry Board (DB), screw spacing, grade of concrete, damping ratio, type of support, and floor span on the dynamic responses of the PSSDBC panels were assessed. Results demonstrated that although some factors reduced dynamic response of the PSSDBC system under human walking load, low frequency PSSDBC floor system could reach high vibration levels resulting in lack of comfortableness for users.

This paper aims to measure natural frequencies of Profiled Steel Sheet Dry Board (PSSDB) with Concrete infill (PSSDBC) system. For this purpose, experimental tests by estimation of Frequency Response Function (FRF) and a numerical method by development of Finite Element Model (FEM) are used. The connection stiffness between Peva45 as Profiled Steel Sheet (PSS) and different concrete grades of 25 (C25), 30 (C30), and 35 (C35) are measured by push-out tests to be used in the FEM. The effect of presence of concrete in the PSSDB system on the natural frequencies such as Fundamental Natural Frequency (FNF) of the system is investigated. The variability in the FNF of the studied system under different parameters such as concrete grades, thicknesses of PSS and Dry Board (DB), and boundary conditions is determined. In a wide numerical study, the FNF of the PSSDBC system with practical dimensions is revealed for different lengths, widths, and boundary conditions. The results help designer predict serviceability and design criteria of the studied panels.